Magnetic tape cartridge

ABSTRACT

A magnetic tape cartridge has a cartridge casing, a single reel around which a magnetic tape is wound and which is contained in the cartridge casing for rotation and a leader pin fixed to the leading end portion of the magnetic tape. The leader pin is provided at its opposite ends with engagement portions which are brought into engagement with a tape drawing mechanism of a recording and reproducing system when the magnetic tape cartridge is loaded in the recording and reproducing system. The end face of each engagement portion is provided with a recess at which the tape drawing mechanism chucks the leader pin.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a magnetic tape cartridge, and moreparticularly to a magnetic tape cartridge comprising a cartridge casingand a single reel around which a magnetic tape is wound and which iscontained in the cartridge casing for rotation.

[0003] 2. Description of the Related Art

[0004] There has been known a single reel magnetic tape cartridgecomprising a flat cartridge casing which is formed by upper and lowershell halves and is substantially square in shape and a single reelaround which a magnetic tape is wound and which is contained in thecartridge casing for rotation. Such a single reel magnetic tapecartridge has been used for retaining data of a computer or the like. Atape outlet opening is formed in a side wall of the cartridge casing andwhen the magnetic tape cartridge is used, i.e., when the magnetic tapecartridge is loaded in a recording and reproducing system as, forinstance, an external storage for a computer and information is to berecorded on the magnetic tape or information recorded on the magnetictape is to be read, the magnetic tape wound around the reel is drawn outthrough the tape outlet opening.

[0005] In such a magnetic tape cartridge of one type, a leader block isfixed to the leading end of a leader tape which is connected to themagnetic tape and when the magnetic tape cartridge is not used, themagnetic tape is fully wound around the reel with the leader blockfitted in the tape outlet opening to close the tape outlet opening. Inthe case of the magnetic tape cartridge of this type, when the magnetictape cartridge is loaded in the recording and reproducing system, adrive means in the recording and reproducing system engages withengagement teeth on the reel exposed outside at the central portion ofthe lower casing half and a tape drawing mechanism in the recording andreproducing system chucks the leader block and draws the magnetic tapeoutside the cartridge casing into a tape running path of the recordingand reproducing system.

[0006] In another type, the tape outlet opening is closed and opened bya lid which is rotatable between a closing position where it closes thetape outlet opening and an opening position where it opens the tapeoutlet opening, the lid being urged by a spring toward the closingposition. A hook member is fixed to the leading end of a leader tapewhich is connected to the magnetic tape and when the magnetic tapecartridge is not used, the magnetic tape is fully wound around the reelwith the hook member retracted inside the tape outlet opening and thelid held in the closing position. In the case of the magnetic tapecartridge of this type, when the magnetic tape cartridge is loaded inthe recording and reproducing system, a drive means in the recording andreproducing system engages with engagement teeth on the reel exposedoutside at the central portion of the lower casing half and a tapedrawing mechanism in the recording and reproducing system moves the lidto the opening position, chucks the hook member and draws the magnetictape outside the cartridge casing into a tape running path of therecording and reproducing system.

[0007] Recently, the recording and reproducing system (will be referredto as “tape drive system” hereinbelow) comes to require employment of aleader pin about 3 mm thick in place of the leader block or the hookmember. However attempts at meeting such requirement have encountered adifficulty that it is difficult for the tape drawing mechanism in thetape drive system to surely chuck such a thin leader pin.

SUMMARY OF THE INVENTION

[0008] In view of the foregoing observations and description, theprimary object of the present invention is to provide a magnetic tapecartridge which is provided with a leader pin which can be surelychucked by the tape drawing mechanism in the tape drive system.

[0009] In the following description, a term “a magnetic tape” sometimesmeans “a magnetic tape with a leader tape connected thereto”.

[0010] The magnetic tape cartridge in accordance with the presentinvention comprises a cartridge casing, a single reel around which amagnetic tape is wound and which is contained in the cartridge casingfor rotation, and a leader pin fixed to the leading end portion of themagnetic tape and is characterized in that the leader pin is provided atits opposite ends with engagement portions which are brought intoengagement with a tape drawing mechanism of a recording and reproducingsystem when the magnetic tape cartridge is loaded in the recording andreproducing system, and the end face of each engagement portion isprovided with a recess at which the tape drawing mechanism chucks theleader pin.

[0011] With this arrangement, though simple in structure, the tapedrawing mechanism of the recording and reproducing system can surelychuck the leader pin.

[0012] It is preferred that each engagement portion be provided with asmaller diameter portion and a flange on the outer side of the smallerdiameter portion and the recess be formed on the outer end face of theflange at the center thereof.

[0013] For example, the leader pin may comprise a body portion providedwith the aforesaid engagement portions at its opposite ends and a clampmember which is press-fitted on the body portion sideways with theleading end portion of the magnetic tape sandwiched therebetween.

[0014] With this arrangement, the leader pin can be easily fixed to theleading end portion of the magnetic tape.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a perspective view showing a magnetic tape cartridge inaccordance with an embodiment of the present invention with the slidedoor closed,

[0016]FIG. 2 is a perspective view showing the magnetic tape cartridgewith the slide door opened,

[0017]FIG. 3 is a side view partly cutaway showing a basic appearance ofthe leader pin,

[0018]FIG. 4A is an exploded perspective view of a first specificexample of the leader pin,

[0019]FIG. 4B is a cross-sectional view of the leader pin,

[0020]FIG. 5 is an exploded perspective view of a second specificexample of the leader pin,

[0021]FIG. 6A is a cross-sectional view of the second specific exampleof the leader pin in an assembled stated,

[0022]FIG. 6B is a view similar to FIG. 6A but showing a modification ofthe second example,

[0023]FIG. 6C is fragmentary cross-sectional view for illustratinganother modification of the second example,

[0024]FIG. 7 is an exploded perspective view of still anothermodification of the second example,

[0025]FIG. 8 is an exploded perspective view of a third specific exampleof the leader pin,

[0026]FIG. 9 is an exploded perspective view of a fourth specificexample of the leader pin,

[0027]FIG. 10 is an exploded perspective view of a fifth specificexample of the leader pin,

[0028]FIG. 11A is an exploded cross-sectional view of the fifth example,

[0029]FIG. 11B is a cross-sectional view of the fifth example in anassembled state,

[0030]FIGS. 12A and 12B are schematic cross-sectional views forillustrating a sixth specific example of the leader pin,

[0031]FIGS. 13A and 13B are schematic cross-sectional views forillustrating a modification of the sixth specific example,

[0032]FIGS. 14A and 14B are schematic cross-sectional views forillustrating another modification of the sixth specific example,

[0033]FIG. 15 is a schematic side view of a seventh specific example ofthe leader pin,

[0034]FIGS. 16A and 16B are cross-sectional views taken along lineXVI-XVI in FIG. 15 before and after clamping the magnetic tape,

[0035]FIGS. 17A and 17B are views similar to FIGS. 16A and 16B butshowing a modification of the seventh example,

[0036]FIG. 18A is a fragmentary perspective view of an eighth specificexample of the leader pin,

[0037]FIG. 18B is a cross-sectional view of the eighth example,

[0038]FIG. 18C is a view similar to FIG. 18B but showing a modificationof the eighth example,

[0039]FIG. 18D is a cross-sectional view showing the leading end portionof the magnetic tape wound around the leader pin,

[0040]FIG. 19A is fragmentary perspective view of another modificationof the eighth example,

[0041]FIG. 19B is a cross-sectional view of the modification,

[0042]FIG. 19C is a view similar to FIG. 19B but showing a still anothermodification of the eighth example,

[0043]FIG. 20 is a side view of a ninth example of the leader pin,

[0044]FIGS. 21A to 21C are cross-sectional views taken along lineXXI-XXI in FIG. 20 showing variations of manner of connecting the leadertape to the leader pin,

[0045]FIG. 21D is a vertical cross-sectional view of FIG. 20 showinganother variation of manner of connecting the leader tape to the leaderpin,

[0046]FIG. 22 is a side view showing a modification of the ninthexample,

[0047]FIG. 23 is an exploded side view of a tenth specific example ofthe leader pin,

[0048]FIG. 24A is a cross-sectional view taken along line A-A in FIG.23,

[0049]FIG. 24B is a cross-sectional view taken along line B-B in FIG.23,

[0050]FIG. 25A is a vertical cross-sectional view of a eleventh exampleof the leader pin,

[0051]FIGS. 25B and 25C are views similar to FIG. 25A but showingmodifications of the eleventh example,

[0052]FIG. 26 is a cross-sectional view taken along line XXVI-XXVI inFIG. 25A,

[0053]FIG. 27 is a view for illustrating the dimensions of importantparts of the eleventh example,

[0054]FIG. 28 is a vertical cross-sectional view of a twelfth example ofthe leader pin,

[0055]FIG. 29 is a perspective view of a thirteenth example of theleader pin,

[0056]FIG. 30 is a perspective view of the pin half in the thirteenthexample,

[0057]FIG. 31 is an exploded side view of the leader pin of thethirteenth example,

[0058]FIG. 32 shows cross-sections of the thirteenth example taken alongdifferent planes,

[0059]FIG. 33 is a cross-sectional view for illustrating a modificationof the thirteenth example,

[0060]FIG. 34 is an exploded side view of a fourteenth specific exampleof the leader pin,

[0061]FIGS. 35A and 35B are cross-sectional views taken along lines A-Aand B-B in FIG. 34,

[0062]FIGS. 36A to 36C are cross-sectional views for illustrating tapeclamping operation of the fourteenth example,

[0063]FIG. 37 is an exploded perspective view of a fifteenth specificexample of the leader pin,

[0064]FIG. 38 is a perspective view of the fifteenth example in anassembled state,

[0065]FIG. 39 is a cross-sectional view of the fifteenth example,

[0066]FIG. 40 is an exploded perspective view of a sixteenth specificexample of the leader pin,

[0067]FIGS. 41A and 41B are views showing different manners ofconnecting the leader tape to the magnetic tape,

[0068]FIGS. 42A to 42C are views showing different manners of clampingthe leading end portion magnetic tape by the leader pin of the precedingexamples,

[0069]FIG. 43 is a perspective view of a modification of the clampmember,

[0070]FIG. 44 is view for illustrating an example of the manner forpress-fitting the clamp member shown in FIG. 43 on the pin body,

[0071]FIG. 45 is a view for illustrating a method of bonding themagnetic tape to the leader pin by use of hot-melt adhesive tape,

[0072]FIG. 46 is a perspective view of a leader pin of another example,

[0073]FIG. 47A is a fragmentary perspective view of a leader pin ofstill another example,

[0074]FIGS. 47B and 47C are fragmentary perspective views showingmodifications of the leader pin,

[0075]FIGS. 48 and 49 are perspective views showing the manner offorming a leader pin-magnetic tape assembly,

[0076]FIG. 50 is a transverse cross-sectional view of FIG. 49,

[0077]FIG. 51 is a fragmentary cross-sectional view showing the insideof the magnetic tape cartridge near the tape outlet opening 2,

[0078]FIG. 52 is a cross-sectional view taken along line X-X in FIG. 41,

[0079]FIG. 52 is a fragmentary perspective view showing a modificationof the guide surface,

[0080]FIG. 53 is a fragmentary perspective view showing anothermodification of the guide surface,

[0081]FIG. 54 is a fragmentary perspective view showing still anothermodification of the guide surface,

[0082]FIG. 55A is a fragmentary cross-sectional view showing stillanother modification of the guide surface, and

[0083]FIG. 55B is a fragmentary cross-sectional view showing stillanother modification of the guide surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0084] In FIGS. 1 and 2, a magnetic tape cartridge in accordance with anembodiment of the present invention comprises a cartridge casing 1formed by upper and lower casing halves 1 a and 1 b and a single reel(not shown) around which a magnetic tape is wound and which is supportedfor rotation in the cartridge casing 1. A tape outlet opening 2 throughwhich the magnetic tape is drawn out is formed in one end face of thecartridge casing 1 near a corner thereof. A slide door 3 for opening andclosing the tape outlet opening 2 is mounted in the cartridge casing 1to be slidable back and forth between a closing position where it closesthe tape outlet opening 2 and opening position where it opens the same.The slide door 3 is urged toward the closing position by a spring notshown disposed between a side face of the cartridge casing 1 and theslide door 3.

[0085] As shown in FIG. 2, a leader pin 4 fixed to the leading end ofthe magnetic tape is held inside the tape outlet opening 2. When themagnetic tape cartridge is loaded in a tape drive system, a reel drivemeans of the tape drive system is brought into engagement withengagement teeth (not shown) on the reel which is exposed in the bottomface of the cartridge casing 1 at the center thereof and a tape drawingmechanism of the tape drive system pushes the front end face 3 a of theslide door 3 to open the slide door 3. Further the tape drawingmechanism chucks the leader pin 4 and pulls the leader pin 4 into thesystem, whereby the magnetic tape is set in the tape drive system sothat data can be recorded on or read out from the magnetic tape.

[0086] A knob 5 for inhibiting erasure and write projects outside in oneside face of the cartridge casing 1.

[0087] As shown in FIG. 3, the leader pin 4 basically comprises a mainportion 11 at which the leading end portion of the magnetic tape isclamped, a pair of small diameter portions 12 which extend from theupper and lower end of the main portion 11 and a pair of flanges 13which are formed on the outside of the small diameter portions 12. Thesmall diameter portions 12 form an engagement portions which are broughtinto engagement with the tape drawing mechanism of the tape drivesystem. Each of the flanges 13 is provided at the center of its end facewith a conical recess 13 a at which the tape drawing mechanism chucksthe leader pin 4. The main portion 11 is substantially equal in lengthto the width (½ inches) of the magnetic tape.

[0088] Examples of the specific structure of the leader pin 4 will bedescribed, hereinbelow. FIG. 4A is an exploded perspective view of theleader pin 4 of a first example and FIG. 4B is a cross-sectional view ofthe same. As shown in FIGS. 4A and 4B, the leader pin 4 of the firstexample comprises a body portion 15 of metal or hard plastic and a clampmember 16 of metal or hard plastic. The body portion 15 has a relativelythick middle portion, a pair of inner flanges 14 on opposite ends of themiddle portion, a pair of small diameter portions 12 on the upper andlower sides of the inner flanges 14 and a pair of outer flanges 13 onthe upper and lower sides of the small diameter portions 12. The clampmember 16 has an axial hole which extends over the entire length of theclamp member 16 and opens outward through a slit 16 a extending over theentire length of the clamp member 16. The clamp member 16 ispress-fitted on the middle portion of the body portion 15 between theinner flanges 14 through the slit 16 a with the leading end portion ofthe magnetic tape 10 pinched between the inner wall surface of the axialhole of the clamp member 16 and the outer surface of the middle portionof the body portion 15 a, whereby the leading end portion of themagnetic tape 10 is fixed to the leader pin 4.

[0089] With this arrangement, the leading end portion of the magnetictape 10 can be easily and surely fixed to the leader pin 4, and theconical recesses on the outer flanges 13 makes it feasible for the tapedrawing mechanism of the tape drive system to surely chuck the leaderpin 4.

[0090] The clamp member 16 may be formed of shape memory alloy insteadof elastic material. In this case, the clamp member 16 is heated andfitted on the middle portion of the body portion 15 between the innerflanges 14 through the slit 16 a with the leading end portion of themagnetic tape 10 pinched between the inner wall surface of the axialhole of the clamp member 16 and the outer surface of the middle portionof the body portion 15. Thereafter the clamp member 16 is cooled tonormal temperatures, whereby the axial hole of the clamp member 16 isreduced in its inner diameter under shape memory effect and the leadingend portion of the magnetic tape 10 is clamped on the outer surface ofthe body portion 15.

[0091] Examples of the specific structures of the leader pin which areprovided with a tape positioning means for positioning the leading endportion of the magnetic tape 10 with respect to the leader pin will bedescribed, hereinbelow.

[0092]FIG. 5 shows a leader pin of a second example. As shown in FIG. 5,the leader pin of this example comprises a pin body 114 of metal or hardplastic. The pin body 114 has a pair of flanges 13 on opposite endsthereof and a shaft portion 115 which extends between the flanges 113and is substantially uniform in diameter. A resilient clamp member 116which is larger than the shaft portion 115 in outer diameter and issmaller than the shaft portion 115 in length is press-fitted on themiddle portion of the shaft portion 115. When the clamp member 116 ispress-fitted on the middle portion of the shaft portion 115, the smalldiameter portions 12 (FIG. 3) are formed on opposite sides of the clampmember 116. A groove 115 a is formed on the shaft portion 115 to extendin the longitudinal direction of the pin body 114.

[0093] The clamp member 116 has an axial hole which extends over theentire length of the clamp member 116 and opens outward through a slit116 a extending over the entire length of the clamp member 116. A flange117 is formed on one edge of the slit 116 a of the clamp member 116 toproject toward the longitudinal axis of the clamp member 116.

[0094] The clamp member 116 is press-fitted on the shaft portion 115 ofthe pin body 114 with the flange 117 engaged with the groove 115 a asshown in FIG. 6A. By bringing the leading edge of the magnetic tape 10into abutment against the inner surface 117 a of the flange 117 whenclamping the leading end portion of the magnetic tape 10 between the pinbody 114 and the clamp member 116, the magnetic tape 10 can be easilypositioned with respect to the leader pin 4. It is preferred that theclamp member 116 be formed of deposition hardened steel such as SUS631in order to increase resiliency of the clamp member 116.

[0095] In the case of this example, since the shaft portion 115 of thepin body 114 is circular in cross-section, the main portion 11 (FIG. 3)formed by fitting the clamp member 116 on the shaft portion 115 cannotbe circular in cross-section. When the shaft portion 115 is in such ashape that forms circular cross-section together with the clamp member116 as shown in FIG. 6B, the main portion 11 formed by fitting the clampmember 116 on the shaft portion 115 can be circular in cross-section.

[0096] Further by forming a groove 117 b on the base of the innersurface 117 a of the flange 117 and inserting the leading end of themagnetic tape 10 in the groove 117 b as shown in FIG. 6C, positioning ofthe leading end portion of the magnetic tape 10 with respect to theleader pin can be more facilitated.

[0097] Further when a short groove 115 b is formed on the shaft portion115 in perpendicular to the groove 115 a to be connected to the groove115 a at one end thereof and a projection 116 b is formed on the clampmember 116 at one end as shown in FIG. 7 so that the projection 116 b isreceived in the short groove 115 b when the clamp member 116 is fittedon the pin body 114, positioning of the magnetic tape 10 with respect tothe leader pin in the axial direction thereof can be facilitated bybringing a side edge of the magnetic tape 10 into abutment against theprojection 116 b.

[0098]FIG. 8 shows a leader pin of a third embodiment in whichpositioning of the magnetic tape 10 with respect to the leader pin inthe axial direction thereof is facilitated. The leader pin of thisexample differs from that of the second example in that the shaftportion 115 is not provided with the groove 115 a and accordingly theclamp member 116 is not provided with the flange 117, and instead theclamp member 116 is provided with a pair of arcuate shoulders 116 cextending from the slit 116 a on opposite ends of the clamp member 116.The magnetic tape 10 is positioned with respect to the leader pin in theaxial direction of the leader pin, i.e., in the transverse direction ofthe magnetic tape 10, by bringing the side edges of the magnetic tape 10into abutment against the shoulders 116 c.

[0099] In the fourth example shown in FIG. 9, the outer diameter of theshaft portion 115 is slightly smaller than that of the small diameterportions 12 and shoulders 115 c are formed between the shaft portion 115and each of the small diameter portion 12. The magnetic tape 10 ispositioned with respect to the leader pin in the axial direction of theleader pin by use of the shoulder 115 c.

[0100] In the fifth example shown in FIG. 10, the pin body 114 is thesame as that shown in FIG. 8 but the magnetic tape 10 is fixed to theleader pin by a pair of split clamp members 118 of plastic. That is, theclamp members 118 are semi-cylindrical in shape and are fixed togetherby adhesive with the pin body 114 and the leading end portion of themagnetic tape 10 intervening therebetween as shown in FIGS. 11A and 11B.The tip of the leading end portion of the magnetic tape 10 projectingoutside the clamp members 118 is cut after bonding the clamp members118. The leader pin of this example is easy to manufacture and isadvantageous in that positioning of the magnetic tape 10 is easy.

[0101] As a sixth example of the leader pin and its modifications, themain portion 11 may be formed of pair of members 119A and 119B which arebrought into resilient engagement with each other with the leadingportion of the magnetic tape 10 pinched therebetween as shown in FIGS.12A and 12B, 13A and 13B and 14A and 14B, respectively. In the examplesshown in FIGS. 12A and 12B and 13A and 13B, the members 119A and 119Bare hinged to each other at H and the example shown in FIGS. 14A and14B, the members 119A and 119B are separate from each other.

[0102] In the seventh example shown in FIGS. 15, 16A and 16B, the mainportion 11 of the leader pin 4 is formed with a slit 120 diametricallythrough the main portion 11. The slit 120 is flared in cross-sectionfrom the center of the main portion 11 toward the opening 120 a on theside opposite to the side from which the leading end portion of themagnetic tape 10 is inserted into the slit 120. After the magnetic tape10 is inserted into the slit 120, a wedge-shaped clamp member 121 ispress-fitted in the slit 120 from the opening 120 a, thereby clampingthe magnetic tape 10 on the main portion 11 as shown in FIG. 16A. Thisexample is advantageous in that the leader pin 4 can be simple instructure. It is preferred that the wedge-shaped clamp member 121 besubstantially the same in the radius of curvature of the outer surfacethereof as that of the leader pin 4.

[0103] In a modification of the seventh example shown in FIGS. 17A and17B, a bifurcated wedge-shaped clamp member 123 is used. The clampmember 123 is provided with a pair of hooks 123 a on the tips of thearms and the main portion 11 of the leader pin 4 is provided with a slit122 which is flared in cross-section from the center of the main portion11 toward the opening 122 a on the side opposite to the side from whichthe leading end portion of the magnetic tape 10 is inserted into theslit 122 and is provided with a pair of shoulders 122 b. When the clampmember 123 is press-fitted in the slit 122 from the opening 122 a, thearms of the member 123 is once resiliently bent toward each other andthen spring away from each other into engagement with the shoulders 122b, whereby the clamp member 123 and the magnetic tape 10 are preventedfrom being disengaged from the slit 122.

[0104] In the eighth example shown in FIGS. 18A to 18D, a slit 124 isformed in the main portion 11 of the leader pin 4 and the leading endportion of the magnetic tape 10 is inserted into the slit 124. Themagnetic tape 10 is held on the leader pin 4 by winding the magnetictape 10 around the main portion 11 with the leading end portion insertedinto the slit 124 as shown in FIG. 18D. In this example, the slit 124may extend either through the main portion 11 as shown in FIG. 18B ornot through the main portion 11 as shown in FIG. 18C.

[0105] The slit 124 may reach the flanges 13 as shown in FIGS. 19A and19B so that the slit 124 can be easily formed, for instance, by wirecutting. Further the slit 124 may be formed so that a thin portion 11 ais formed on the outer side of the slit 124 as shown in FIG. 19C and themagnetic tape 10 may be held in the slit 124 under the resiliency of thethin portion 11 a.

[0106] In the ninth example shown in FIG. 20, the magnetic tape 10 isconnected to a temperature-resistant connecting sheet 125. That is, theleader pin 4 is formed by plastic molding and when the leader pin 4 ismolded, the connecting sheet 125 is inserted so that the connectingsheet 125 is projected from the leader pin 4 as shown in FIG. 21A. Theconnecting sheet 125 is substantially equal in width to the magnetictape 10 and the leading end portion of the magnetic tape 10 is connectedto the connecting sheet 125, for instance, by use of splicing tape 126.

[0107] By forming a bent portion 125 a or 125 b in the end portion ofthe connecting tape 125 as shown in FIGS. 21B or 21C or forming a smallopening 125 c in the end portion of the connecting tape 125 as shown inFIG. 21D, bonding strength of the connecting sheet 125 to the leader pin4 can be increased.

[0108] The magnetic tape 10 may be bonded to the connecting sheet 125 byheat-sensitive adhesive as shown in FIG. 22.

[0109] In the tenth example shown in FIG. 23, a leader tape 128 such asphotographic film which has suitable strength and rigidity is connectedto the leading end of the magnetic tape 10, for instance, by use ofsplicing tape 126 and a slit 129 is formed in the leader pin 4. Theleader tape 128 is provided with a pair of engagement holes 128 a onupper and lower edges thereof.

[0110] Further as shown in FIGS. 24A and 24B, a pair of engagementprojections 130 projects from one side wall of the slit 129 and aretainer projection 131 projects from the other side wall of the slit129 at the middle between the engagement projections 130. The leadertape 128 is inserted into the slit 129 and the engagement holes 128 aare brought into engagement with the engagement projections 130 as shownin FIG. 24A. The retainer projection 131 pushes the leader tape 128toward the engagement projections 130, thereby preventing the engagementholes 128 a from being disengaged from the engagement projections 130 asshown in FIG. 24B.

[0111] This example is advantageous in that the leader tape 128 can beeasily connected to the leader pin 4.

[0112] In the eleventh example shown in FIGS. 25A to 25C, the pin body114 is provided with a pair of inner flanges 132 which separates theshaft portion 115 from the small diameter portions 12 and a clamp member116 which is C-shaped in cross-section is press-fitted on the shaftportion 115 between the inner flanges 132 as shown in FIG. 26. The innerflanges 132 are spaced from each other by a distance substantially equalto the width of the magnetic tape 10 and are used to position themagnetic tape 10 with respect to the leader pin 4.

[0113] When the distance between the outer surface of the small diameterportion 12 and the outer surface of the outer flange 13 is representedby h, the distance between the outer surface of the shaft portion 115and the outer surface of the inner flange 13 is represented by a, andthe distance between the outer surface of the small diameter portion 12and the outer surface of the inner flange 132 is represented by b asshown in FIG. 27, at least one of a and b is not larger than 2h/3 in anyone of the leader pins shown in FIGS. 25A to 25C.

[0114] In the leader pin shown in FIG. 25A, the outer diameter of theshaft portion 115 is equal to that of the small diameter portion 12 anda=b≦2h/3. The clamp member 116 has a length slightly smaller than thedistance between the inner flanges 132.

[0115] In the leader pin shown in FIG. 25B, the outer diameter of theshaft portion 115 is also equal to that of the small diameter portion 12but the clamp member 116 has a length substantially equal to thedistance between the inner flanges 132. The clamp member 116 is providedwith an annular recess 133 at each end face thereof and the innerflanges 132 are received in the recesses 133 when the clamp member 116is fitted on the pin body 114.

[0116] In the leader pin shown in FIG. 25C, the diameter of the innerflanges 132 is substantially equal to that of the outer flanges 13 andaccordingly b=h. However since the shaft portion 115 is larger indiameter than the small diameter portions 12, a≦2h/3. Accordingly, theclamp member 116 is thinner than that employed in the leader pin shownin FIGS. 25A or 25B and is formed of hoop (stainless steel or the likeis preferred in view of resistance to corrosion and/or hardness tomagnetize.

[0117] Thus in the leader pins of this example, positioning of themagnetic tape 10 and the clamp member 116 is facilitated by virtue ofthe inner flanges 132 and at the same time even if the inner flanges 132are small in thickness (about 0.4 to 0.6 mm), there arises no problemwith respect to the strength and/or productivity of the leader pinssince the height of the inner flanges 132 from the outer surface of theshaft portion 115 and/or the small diameter portions 12 satisfies theaforesaid condition.

[0118] In the twelfth example shown in FIG. 28, a pair of annularrecesses 134 are formed on the pin body 112 between the shaft portion115 and the small diameter portions 12, and a pair of annularprotrusions 135 are formed on the inner peripheral surfaces of the clampmember 116 at the ends thereof. The annular protrusions 135 are receivedin the annular recesses 134 on the pin body 114 when the clamp member116 is fitted on the pin body 114.

[0119] With this arrangement, the clamp member 116 can be accuratelypositioned with respect to the pin body 114. Further the magnetic tape10 can be accurately positioned with respect to the leader pin 4 byvirtue of the annular protrusions 135 on the clamp member 116. Furtherthe annular protrusions 135 protects the side edges of the magnetic tape10 when the tape drawing mechanism of the tape drive system is broughtinto engagement with the small diameter portions 12. Further since theinner flanges are not used, problems which arise when inner flangessmall in thickness and large in height are used can be avoided.

[0120] In the thirteenth example shown in FIGS. 29 to 32, the leader pin4 is formed by left and right pin halves 4L and 4R which are buttedtogether along a plane P including the longitudinal axis of the leaderpin 4.

[0121] As shown in FIG. 30, the left pin half 4L has an elongated groove136 formed on the plane P to extend in the longitudinal direction of thepin half 4L and an elongated protrusion 137 formed on the plane P toextend in the longitudinal direction of the pin half 4L in a positionsymmetrical to the position of the groove 136 about the center line. Athrough hole 138 is formed in the upper flange 13 to extend from theplane P to the outer surface of the flange 13 while an engagementprojection 139 is formed on the lower flange 13 to project from theplane P. The through hole 138 is provided with a pair of engagementshoulders 138 a and the engagement projection 139 comprises a pair ofresilient engagement pieces 139 a each having a hook portion 139 aprojecting outward.

[0122] The right pin half 4R is identical to the left pin half 4L exceptthat the right pin half 4R is positioned upside down relative to theleft pin half 4L. That is, when the left and right pin halves 4L and 4Rare butted together with the leading end portion of the magnetic tape 10intervening therebetween, the engagement projection 138 a on each of theleft and right pin halves 4L and 4R is inserted into the through hole138 of the other pin half, and the protrusion 137 of each of the leftand right pin halves 4L and 4R is inserted into the grooves 136 of theother pin half as shown in FIG. 32. The hook portions 139 b of theengagement projections 139 a are engaged with the engagement shoulders138 a of the through holes 138 and hold together the left and right pinhalves 4L and 4R with the magnetic tape 10 pinched therebetween. It ispreferred that the radius of curvature of the end faces of theengagement pieces 139 a be equal to that of the outer surfaces of theflanges 13 so that the outer surfaces of the flanges 13 formed by thepin halves 4L and 4R become smooth.

[0123] Further the magnetic tape 10 is firmly clamped between the leftand right pin halves 4L and 4R by virtue of the engagement between thegrooves 136 and the protrusions 137.

[0124] This example is advantageous from the viewpoint of productivityin that the leader pin can be formed by two identical members andassembly of the leader pin and clamp of the magnetic tape 10 can beeffected at one time by simply pressing the left and right halves 4L and4R against each other.

[0125] Instead of fixing the pin halves 4L and 4R to each other byengagement of the flanges 13 as in the thirteenth example, the pinhalves 4L and 4R may be fixed to each other by fitting a projection 142on one of the flanges in a recess 141 on the other flange as shown inFIG. 33 and bonding the pin halves 4L and 4R by adhesive. Thisarrangement is advantageous in that no hole is formed on the outersurfaces of the flanges.

[0126] In the fourteenth example shown in FIGS. 34, 35A, 35B and 36A to36C, the leader pin 4 is formed by first and second members 4M and 4S.The first member 4M is provided with a main portion 11 in the form of ahollow cylindrical member having an axial hole 143 and a slit 144communicated with the axial hole 143. One of the small diameter portions12 and one of the flanges 13 are formed on the upper end of the mainportion 11 and the axial hole 143 opens in the lower end face of themain portion 11 which is flat. The second member 4S has a shaft portion145 which is inserted for rotation into the axial hole 143 of the firstmember 4M and the other small diameter portion 12 and the other flange13 are formed on the lower end face of the shaft portion 145. The shaftportion 145 is semi-circular in cross-section and has a flat sidesurface 145 a.

[0127] When the leader pin 4 is assembled, the shaft portion 145 of thesecond member 4S is inserted into the axial hole 143 of the first member4M with the flat surface 145 a faced so that a space 146 communicatedwith the slit 144 is formed inside the axial hole 143 as shown in FIG.36A. Then the leading end portion of the magnetic tape 10 is insertedinto the space 146 through the slit 144 as shown in FIG. 36B, and thenthe shaft portion 145 is rotated counterclockwise so that the magnetictape 10 is pinched between the inner surface of the axial hole 143 andthe arcuate outer surface of the shaft portion 145 as shown in FIG. 36C.This example is advantageous in that the leader pin is easy to assemble.

[0128] The leading end portion of the magnetic tape 10 may be insertedinto the axial hole 143 before the shaft portion 145 is inserted intothe axial hole 143.

[0129] In the fifteenth example shown in FIGS. 37 to 39, the leader pin4 comprises a pin body 114 and a clamp member 116 which is fitted on thepin body 114 to form the main portion 11. The pin body 114 has a shaftportion 115 which is substantially equal in outer diameter to the smalldiameter portions 12. A protrusion 147 is formed on the outer surface ofthe shaft portion 115 to extend in the longitudinal direction of the pinbody 114 and a pair of short protrusions 147 a for positioning themagnetic tape 10 are formed at the ends of the protrusion 147 to extendin a circumferential direction of the shaft portion 115.

[0130] As shown in FIG. 39, the protrusion 147 is shaped so that themain portion 11 formed when the clamp member 116 is fitted on the shaftportion 115 is substantially circular in cross-section.

[0131] The protrusion 147 facilitates positioning of the leading end ofthe magnetic tape 10 in the longitudinal direction of the tape 10 andthe short protrusions 147 a facilitate positioning of the magnetic tape10 in the transverse direction thereof.

[0132] In the sixteenth example shown in FIGS. 40, 41A and 41B, a loopof a leader tape 148 is connected to the leading end of the magnetictape 10 and the pin body 114 is inserted into the loop of the leadertape 148 so that the shaft portion 115 is opposed to the leader tape148. Then the magnetic tape 10 is pulled leftward as seen in FIG. 40 sothat the leader tape 148 is brought into close contact with the shaftportion 115 and then the clamp member 116 is press-fitted on the shaftportion 115 with the leader tape 148 intervening therebetween.

[0133] The loop of the leader tape 148 may be made around the pin body114 after placing the pin body 114 on the first leader tape. Further themagnetic tape 10 may be connected to the leader pin by way of a loop ofa splicing tape in place of the loop of the leader tape.

[0134] The leader tape 148 may be bonded to the magnetic tape 10 by useof splicing tape 149 as shown in FIG. 41A. Otherwise, heat-sensitiveadhesive may be applied to the inner surface of the leader tape 148 andthe opposite ends of the leader tape 148 may be bonded to opposite sidesof the leading end portion of the magnetic tape 10 as shown in FIG. 41Bby applying heat to the opposite ends of the leader tape 148 with theleading end portion of the magnetic tape 10 sandwiched therebetween. Inthis case, the leader tape 148 may be bonded to the shaft portion 115 bythe heat-sensitive adhesive, if desired.

[0135] It is possible to use a heat-shrinkable leader tape 148 and fixthe leader tape 148 to the shaft portion 115 by heating and shrinkingthe loop of the leader tape 148 after the shaft portion 115 is insertedinto the loop. In this case, the clamp member 116 may be eliminated.

[0136] In this example, even when the leader tape 148 is connected tothe magnetic tape 10 by use of a splicing tape 149, the length d of thespliced portion can be short as shown in FIG. 41A, whereby adverseeffect of the shoulders formed at the spliced portion can be avoidedwhen the leader pin is drawn into the tape drive system.

[0137] In the case where the clamp member 116 is formed of syntheticresin, there is fear that tape holding strength of the clamp member 116is weakened due to expansion and/or reduction in coefficient ofelasticity of the resin when the leader pin is stored or used under anelevated temperature. When the clamp member 116 is formed of crystallineresin such as polyamide, polyoxymethylene or polybutylene terephthalateand the temperature of the mold is set lower than the normal temperaturewhen molding the clamp member 116 so that the resin becomes low incrystallinity, reduction in the tape holding strength of the clampmember 116 can be avoided since the crystallinity of the resin isincreased to shrink the clamp member 16 and the coefficient ofelasticity of the clamp member 116 increased as the temperatureincreases.

[0138] Further when the outer surface of the shaft portion 115 and/orthe inner surface of the clamp member 116 is roughened by graining,etching, spark erosion or the like, disengagement of the magnetic tape10 from the leader pin can be prevented.

[0139] When the surface roughness Rz of the surfaces is too small, thetape holding force becomes poor and when the surface roughness of thesurfaces is too large, ejection of the clamp member 116 from the moldbecomes difficult, scrapings of resin are produced when the clamp member116 is press-fitted on the pin body 114 and/or the magnetic tape 10 canbe broken. Accordingly the surface roughness Rz is preferably in therange of 0.7 μm≦Rz≦30 μm and more preferably in the range of 1 μm≦Rz≦20μm.

[0140] Further when the clamp member 116 is press-fitted on the shaftportion 115 of the pin body 114 with the magnetic tape 10 interveningtherebetween, air can be trapped between the magnetic tape 10 and theclamp member 116 and the magnetic tape 10 is wrinkled. This problem canbe overcome by forming a slit or a hole in the clamp member 116 at thecenter thereof.

[0141] In the examples where the clamp member 116 is press-fittedsideways on the shaft portion 115 with the magnetic tape 10 interveningtherebetween out of the examples described above, there is fear that themagnetic tape 10 is broken especially when the magnetic tape 10 is thin.This problem can be overcome by folding the leading end portion of themagnetic tape 10 in two or more as shown in FIGS. 42A to 42C andpress-fitting clamp member 116 on the shaft portion 115 with the foldedportion 150 of the magnetic tape 10 intervening therebetween. The foldedportion 50 also functions as a damper when the magnetic tape 10 ispulled.

[0142] Further it is preferred that the clamp member 116 be providedwith a flat portion 116 f on at least one part of the outer surfacethereof as shown in FIG. 43. For example, when the clamp member 116 ispress-fitted on the pin body 114, the clamp member 116 is held byholding jigs 151 with its slit faced downward above the pin body 114 andthe magnetic tape 10 supported on a support 153 and is pressed againstthe shaft portion 115 by a pusher tool 152.

[0143] Accordingly when the flat portions 116 f are in parallel to thedirection of pushing the clamp member 116 by the pusher tool 152,positioning of the clamp member 116 with respect to the holding jigs151. A flat portion 116 f on the side of the clamp member 116 oppositeto the slit limits the direction of pushing the clamp member 116 by thepusher tool 152 and ensures the area at which the pusher tool 152 pushesthe clamp member 116. Further when a flat portion 115 f is provided onthe pin body 114 at the portion facing the support 153, the pin body 114can stably supported on the support 153.

[0144] The magnetic tape 10 may be directly bonded to the leader pin byuse of hot-melt adhesive tape 154 and a hot pressing tool 155 as shownin FIG. 45. Use of the hot-melt adhesive tape is advantageous in thatthe adhesive layer can be more uniform in thickness than when adhesiveis used and it is not necessary to use solvent.

[0145] It is preferred that the outer peripheral surface of each flange13 be provided with non-skid treatment such as knurling, diamondknurling and splining. This is for preventing slip of the leader pinwhen the leader pin is chucked by an assembly jig during assemble of themagnetic tape cartridge or by the tape drawing mechanism of the tapedrive system.

[0146] In the example shown in FIG. 46, the outer peripheral surfaces ofthe flanges 13 are splined as indicated at K.

[0147] It is further preferred that the leader pin be provided with acutaway portion for determining the angular position of the leader pinin order to facilitate positioning the leader pin when connecting themagnetic tape to the leader pin and when the leader pin is incorporatedin the cartridge casing.

[0148] In the example shown in FIG. 47A, the upper flange 13 is providedwith a pair of parallel flat surfaces S. The flat surfaces S areparallel to each other and to the direction in which the magnetic tape20 extends from the leader pin. As shown by the chained line in FIG.47A, an assembly jig 100 chucks the leader pin at the flat surfaces S,whereby the assembly jig 100 can chuck the leader pin constantly in apredetermined angular position.

[0149] As shown in FIGS. 47B and 47C, the flat surfaces S may be formedonly a part of the flange 13 as seen in the direction of thickness ofthe flange 13.

[0150] It is generally required that the main portion 11 of the leaderpin has a predetermined outer diameter when the leader pin isincorporated in the cartridge casing. In some of the preceding examples,this requirement can be met by properly selecting the outer diameter ofthe clamp member 116. However this requirement may also be met withoutuse of the clamp member.

[0151] That is, in the example shown in FIGS. 48 to 50, the leader pin 4comprises a shaft portion 115, a pair of inner flanges 132 on oppositeends of the shaft portion 115, a pair of small diameter portions 12 onthe outer sides of the inner flanges 132 and a pair of outer flanges 13on the outer sides of the small diameter portions 12. The inner flanges132 are substantially equal in outer diameter to the outer flanges 13.The leading end of the magnetic tape 10 is tacked to the outer surfaceof the shaft portion 115 by adhesive, water or alcohol and the magnetictape 10 is wound around the shaft portion 115 until the outer diameterof the tape roll 216 becomes substantially equal to that of the innerflanges 132 while applying light tension to the magnetic tape 10. Thenthe magnetic tape 10 is bonded to the outermost run of the tape roll 216by adhesive as shown in FIGS. 48 to 50. In FIG. 50, reference numeral217 denotes adhesive, water or alcohol for tacking the leading end ofthe magnetic tape 10 to the shaft portion 115 and reference numeral 218denotes the adhesive for bonding the magnetic tape 10 to the outermostrun of the tape roll 216. In this state, the leader pin 4 isincorporated in the cartridge casing.

[0152] In any one of the preceding examples, it is preferred that theleader pin be formed of corrosion resistant material. As thecorrosion-resistant material, plastic materials such as aliphaticpolyamides (e.g., nylon 6, nylon 66(6,6; 6/6) and the like), aromaticpolyamide, polycarbonate, polybutylene terephthalate, polyphenylenesulfide, polymethyl methacrylate, polyoxymethylene, and the like,plastic materials having an imide group such as polyimide,polyamide-imide, polyether-imide and the like, stainless steel materialssuch as SUS304, SUS306, SUS316, SUS410 and the like may be employed.These materials are also advantageous in that they are hard tomagnetize. That is, when the leader pin is magnetized, magnetism of theleader pin can affect the information recorded on the magnetic tape.When the leader pin is to be formed of the aforesaid plastic materials,it is preferred that the plastic materials be reinforced with glassfibers or carbon fibers.

[0153] Further the leader pin may be provided with hard chrome plating.

[0154] As shown in FIG. 51, the leader pin 4 on the leading end of themagnetic tape 10 is held in a recess 228 formed inside the tape outletopening 2 by a pair of spring members 230 which press the flanges 13 ofthe leader pin 4 against the inner surface of the recess 228 when themagnetic tape cartridge is not used.

[0155] As shown in FIG. 52, guide surfaces 229 for guiding the leaderpin 4 into the recess 228 are formed on the inner surfaces of the upperand lower casing halves 1 a and 1 b. It is preferred that the peripheraledges of the upper and lower flanges 13 be chamfered so that they cansmoothly slide on the guide surfaces 229. The recess 228 has upper andlower inner surfaces which are flat and spaced from each other by adistance substantially equal to the length of the leader pin 4. Theguide surfaces 229 are inclined so that they linearly approach eachother toward the recess 228. The slide door 3 is slid back and forthacross the guide surfaces 229 and the upper and lower faces 3 a of theslide door 3 are inclined to conform to the shape of the guide surfaces229.

[0156] When the magnetic tape 10 is rewound and the leader pin 4 isretracted into the recess 228, the flanges 13 slide on the upper andlower guide surfaces 229 and the leader pin 4 is successfully retractedinto the recess 228 even if the center of the leader pin 4 is shiftedfrom the center of the recess 228.

[0157] Though, in this embodiment, the space between the upper and lowerguide surfaces 229 linearly changes, it may change curvilinearly. Thatis, each guide surface 229 may be curved. In such a case, the upper andlower end faces 3 a of the slide door 3 are shaped to conform to theshape of the guide surfaces 229.

[0158]FIG. 53 shows a modification of the guide surface 229. In thismodification, the guide surface 229 is provided with a V-shaped groove233 which extends from the tape outlet opening 2 to the flat recess 288.The groove 233 is formed over the entire width of the guide surface 299and becomes shallower toward the recess 228.

[0159] With this arrangement, the flange 13 of the leader pin 4 slidesalong the center of the guide surface 229 at which the groove 233 isdeepest and is smoothly guided to the recess 228 in an erected position.

[0160] In another modification shown in FIG. 54, the guide surface 229is provided with a V-shaped groove 234 which extends from the tapeoutlet opening 2 to the flat recess 288 and becomes smaller in widthtoward the recess 228.

[0161] With this arrangement, the flange 13 of the leader pin 4 slidesalong the center of the guide surface 229 at which the groove 234 isdeepest and as the flange 13 approaches the recess 228, the flange 13comes to run onto the flat surfaces on opposite sides of the groove 234,whereby the leader pin 4 can be smoothly guided into the recess 228.

[0162] As shown in FIGS. 55A and 55B, the guide surface 229 may beprovided with V-shaped groove 235 or U-shaped groove 236 only at themiddle portion thereof.

[0163] In FIGS. 53, 54, 55A and 55B, reference numeral 237 denotes asliding groove along which the slide door 3 is slit. The grooves 233 and234 in the modifications shown in FIGS. 53 and 54 may be U-shaped incross-section.

[0164] The guide surface and/or the surface of the sliding groove 237may be subjected to treatment for reducing friction so that the leaderpin 4 or the slide door 3 slides more smoothly.

[0165] The treatment may involve, for instance, embossing, applicationof lubricant such as silicone, or application of a low friction sheet.

What is claimed is;
 1. A magnetic tape cartridge comprising a cartridgecasing, a single reel around which a magnetic tape is wound and which iscontained in the cartridge casing for rotation and a leader pin fixed tothe leading end portion of the magnetic tape, wherein the improvementcomprises that the leader pin is provided at its opposite ends withengagement portions which are brought into engagement with a tapedrawing mechanism of a recording and reproducing system when themagnetic tape cartridge is loaded in the recording and reproducingsystem, and the end face of each engagement portion is provided with arecess at which the tape drawing mechanism chucks the leader pin.
 2. Amagnetic tape cartridge comprising a cartridge casing, a single reelaround which a magnetic tape is wound and which is contained in thecartridge casing for rotation and a leader pin fixed to the leading endportion of the magnetic tape, wherein the improvement comprises that theleader pin comprises a pin body which is provided at its opposite endswith engagement portions which are brought into engagement with a tapedrawing mechanism of a recording and reproducing system when themagnetic tape cartridge is loaded in the recording and reproducingsystem, and a clamp member which is provided with a slit extending inthe longitudinal direction thereof and is resiliently press-fittedsideways on the pin body with the leading end portion of the magnetictape intervening therebetween, thereby clamping the leading end portionof the magnetic tape on the leader pin, and that a positioning meanswhich positions the leading end portion of the magnetic tape withrespect to the leader pin is provided on at least one of the pin bodyand the clamp member.
 3. A magnetic tape cartridge comprising acartridge casing, a single reel around which a magnetic tape is woundand which is contained in the cartridge casing for rotation and a leaderpin fixed to the leading end portion of the magnetic tape, wherein theimprovement comprises that the leader pin comprises a pin body which isprovided at its opposite ends with engagement portions which are broughtinto engagement with a tape drawing mechanism of a recording andreproducing system when the magnetic tape cartridge is loaded in therecording and reproducing system, and a pair of members which are bondedtogether with the pin body and the leading end portion of the magnetictape intervening therebetween.
 4. A magnetic tape cartridge comprising acartridge casing, a single reel around which a magnetic tape is woundand which is contained in the cartridge casing for rotation and a leaderpin fixed to the leading end portion of the magnetic tape, wherein theimprovement comprises that the leader pin is provided with a tape clampportion which is hinged to the leader pin and resiliently fitted on theleader pin with the leading end portion of the magnetic tape pinchedtherebetween, thereby clamping the leading end portion of the magnetictape on the leader pin.
 5. A magnetic tape cartridge comprising acartridge casing, a single reel around which a magnetic tape is woundand which is contained in the cartridge casing for rotation and a leaderpin fixed to the leading end portion of the magnetic tape, wherein theimprovement comprises that the leader pin is provided with a slitextending in the longitudinal direction thereof and the magnetic tape isclamped on the leader pin with its leading end portion inserted into theslit and held there by a wedge shaped clamp member press-fitted in theslit.
 6. A magnetic tape cartridge comprising a cartridge casing, asingle reel around which a magnetic tape is wound and which is containedin the cartridge casing for rotation and a leader pin fixed to theleading end portion of the magnetic tape, wherein the improvementcomprises that the leader pin is provided with a slit extending in thelongitudinal direction thereof and the magnetic tape is wound around theleader pin with its leading end portion inserted into the slit.
 7. Amagnetic tape cartridge comprising a cartridge casing, a single reelaround which a magnetic tape is wound and which is contained in thecartridge casing for rotation and a leader pin fixed to the leading endportion of the magnetic tape, wherein the improvement comprises theleader pin is formed plastic molding with one end portion of atemperature-resistant sheet inserted thereinto and the leading end ofthe magnetic tape is connected to the other end of thetemperature-resistant sheet.
 8. A magnetic tape cartridge comprising acartridge casing, a single reel around which a magnetic tape is woundand which is contained in the cartridge casing for rotation and a leaderpin fixed to the leading end portion of the magnetic tape, wherein theimprovement comprises that one end of a leader sheet is connected to theleading end of the magnetic tape, the other end of the leader sheet isinserted into a slit formed in the leader pin and an engagement meanswhich connects the leader sheet to the leader pin is provided on theleader sheet and the leader pin.
 9. A magnetic tape cartridge comprisinga cartridge casing, a single reel around which a magnetic tape is woundand which is contained in the cartridge casing for rotation and a leaderpin fixed to the leading end portion of the magnetic tape, wherein theimprovement comprises that the leader pin comprises a pin body which isprovided with a shaft portion on which the leading end portion of themagnetic tape is attached, a pair of engagement portions which areformed on opposite ends of the shaft portion and brought into engagementwith a tape drawing mechanism of a recording and reproducing system whenthe magnetic tape cartridge is loaded in the recording and reproducingsystem, a pair of inner flanges formed between the shaft portion and theengagement portions and a pair of outer flanges which are formed on theouter ends of the engagement portions and are removably held in thecartridge casing, and a clamp member which is press-fitted sideways onthe pin body with the leading end portion of the magnetic tapeintervening therebetween, thereby clamping the leading end portion ofthe magnetic tape on the leader pin, and that when the distance betweenthe outer surface of the engagement portion and the outer surface of theouter flange is represented by h, the distance between the outer surfaceof the shaft portion and the outer surface of the inner flange isrepresented by a, and the distance between the outer surface of theengagement portion and the outer surface of the inner flange isrepresented by b, at least one of a and b is not larger than 2h/3.
 10. Amagnetic tape cartridge as defined in claim 9 in which the clamp memberis provided with an annular recess on each end face thereof and theinner flange on the pin body is received in the annular recess.
 11. Amagnetic tape cartridge comprising a cartridge casing, a single reelaround which a magnetic tape is wound and which is contained in thecartridge casing for rotation and a leader pin fixed to the leading endportion of the magnetic tape, wherein the improvement comprises that theleader pin comprises a pin body which is provided with a shaft portionon which the leading end portion of the magnetic tape is attached, apair of engagement portions which are formed on opposite ends of theshaft portion and brought into engagement with a tape drawing mechanismof a recording and reproducing system when the magnetic tape cartridgeis loaded in the recording and reproducing system, a pair of annulargrooves formed between the shaft portion and the engement portions and apair of outer flanges which are formed on the outer ends of theengagement portions and are removably held in the cartridge casing, anda clamp member which is provided with protrusions on its ends and ispress-fitted sideways on the pin body with the protrusions received inthe annular grooves and with the leading end portion of the magnetictape intervening therebetween, thereby clamping the leading end portionof the magnetic tape on the leader pin.
 12. A magnetic tape cartridgecomprising a cartridge casing, a single reel around which a magnetictape is wound and which is contained in the cartridge casing forrotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that the leader pincomprises a pair of pin halves which are mated with each other withtheir contact surfaces abutted against each other along a planeincluding the longitudinal axis of the leader pin, the pin halves beingprovided with recesses and projections on their contact surfaces so thatwhen the pin halves are mated with each other with their contactsurfaces abutted against each other and with one of the pin halveinverted relative to the other, the projections on each pin half isinserted into the recess on the other, and the leading end portion ofthe magnetic tape is pinched between the pin halves.
 13. A magnetic tapecartridge comprising a cartridge casing, a single reel around which amagnetic tape is wound and which is contained in the cartridge casingfor rotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that the leader pincomprises a hollow cylindrical member provided with an axial hole and aslit which is formed on the outer surface of the cylindrical member tocommunicate with the axial hole and to extend in the longitudinaldirection of the cylindrical member, and a shaft member which issubstantially semi-circular in cross-section and is inserted into theaxial hole of the cylindrical member to be rotatable therein, the shaftmember being first positioned in a position where it permits insertionof the leading end portion of the magnetic tape into the axial holethrough the slit and then rotated, after the leading end portion of themagnetic tape is inserted into the axial hole, to a position where itpinches the leading end portion of the magnetic tape together with theinner surface of the axial hole.
 14. A magnetic tape cartridgecomprising a cartridge casing, a single reel around which a magnetictape is wound and which is contained in the cartridge casing forrotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that the leader pincomprises a pin body which is provided at its opposite ends withengagement portions which are brought into engagement with a tapedrawing mechanism of a recording and reproducing system when themagnetic tape cartridge is loaded in the recording and reproducingsystem, and a clamp member which is provided with a slit extending inthe longitudinal direction thereof and is resiliently press-fittedsideways on the pin body with the leading end portion of the magnetictape intervening therebetween, thereby clamping the leading end portionof the magnetic tape on the leader pin, a protrusion being formed on theouter surface of the pin body to extend in the longitudinal direction ofthe pin body and to fill the slit of the clamp member when the clampmember is fitted on the pin body.
 15. A magnetic tape cartridgecomprising a cartridge casing, a single reel around which a magnetictape is wound and which is contained in the cartridge casing forrotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that the leader pincomprises a pin body which is provided at its opposite ends withengagement portions which are brought into engagement with a tapedrawing mechanism of a recording and reproducing system when themagnetic tape cartridge is loaded in the recording and reproducingsystem, and a clamp member which is resiliently press-fitted sideways onthe pin body with a loop of a leader tape connected to the leading endportion of the magnetic tape fitted on the pin body, thereby clampingthe leader tape on the leader pin.
 16. A magnetic tape cartridgecomprising a cartridge casing, a single reel around which a magnetictape is wound and which is contained in the cartridge casing forrotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises a loop ofheat-shrinkable leader tape is connected to the leading end of themagnetic tape and the leading tape is heated after it is fitted on theleader pin so that the loop of the leader tape is shrunken and fixed tothe leader pin.
 17. A magnetic tape cartridge comprising a cartridgecasing, a single reel around which a magnetic tape is wound and which iscontained in the cartridge casing for rotation and a leader pin fixed tothe leading end portion of the magnetic tape, wherein the improvementcomprises that the leader pin comprises a pin body which is provided atits opposite ends with engagement portions which are brought intoengagement with a tape drawing mechanism of a recording and reproducingsystem when the magnetic tape cartridge is loaded in the recording andreproducing system, and a clamp member which is provided with a slitextending in the longitudinal direction thereof and is resilientlypress-fitted sideways on the pin body with the leading end portion ofthe magnetic tape intervening therebetween, thereby clamping the leadingend portion of the magnetic tape on the leader pin, a rough surfacebeing provided on the surface of the pin body which is brought intocontact with the magnetic tape and/or the surface of the clamp memberwhich is brought into conatct with the magnetic tape.
 18. A magnetictape cartridge comprising a cartridge casing, a single reel around whicha magnetic tape is wound and which is contained in the cartridge casingfor rotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that the leader pincomprises a pin body which is provided at its opposite ends withengagement portions which are brought into engagement with a tapedrawing mechanism of a recording and reproducing system when themagnetic tape cartridge is loaded in the recording and reproducingsystem, and a clamp member which is provided with a slit extending inthe longitudinal direction thereof and is resiliently press-fittedsideways on the pin body with the leading end portion of the magnetictape intervening therebetween, thereby clamping the leading end portionof the magnetic tape on the leader pin, the leading end portion of themagnetic tape clamped by the clamp member being folded.
 19. A magnetictape cartridge comprising a cartridge casing, a single reel around whicha magnetic tape is wound and which is contained in the cartridge casingfor rotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that the leader pincomprises a pin body which is provided at its opposite ends withengagement portions which are brought into engagement with a tapedrawing mechanism of a recording and reproducing system when themagnetic tape cartridge is loaded in the recording and reproducingsystem, and a clamp member which is provided with a slit extending inthe longitudinal direction thereof and is resiliently press-fittedsideways on the pin body with the leading end portion of the magnetictape intervening therebetween, thereby clamping the leading end portionof the magnetic tape on the leader pin, the clamp member being providedwith at least one flat portion on the outer surface thereof.
 20. Amagnetic tape cartridge comprising a cartridge casing, a single reelaround which a magnetic tape is wound and which is contained in thecartridge casing for rotation and a leader pin fixed to the leading endportion of the magnetic tape, wherein the improvement comprises that achucking portion is formed on a part of the leader pin and the chuckingportion is provided with an anti-slip treatment.
 21. A magnetic tapecartridge comprising a cartridge casing, a single reel around which amagnetic tape is wound and which is contained in the cartridge casingfor rotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that a cutaway portionis formed on the leader pin for determining the angular position of theleader pin with respect to the position on the leader pin in which themagnetic tape is fixed to the leader pin.
 22. A magnetic tape cartridgecomprising a cartridge casing, a single reel around which a magnetictape is wound and which is contained in the cartridge casing forrotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that the leader pin isformed of a corrosion-resistant material.
 23. A magnetic tape cartridgeas defined in claim 22 in which the corrosion-resistant material isplastic.
 24. A magnetic tape cartridge comprising a cartridge casing, asingle reel around which a magnetic tape is wound and which is containedin the cartridge casing for rotation and a leader pin fixed to theleading end portion of the magnetic tape, wherein the improvementcomprises that the leader pin comprises a pin body comprises a pin bodywhich is provided with a shaft portion around which the leading endportion of the magnetic tape is wound and a pair of engagement portionswhich are formed on opposite ends of the shaft portion and brought intoengagement with a tape drawing mechanism of a recording and reproducingsystem when the magnetic tape cartridge is loaded in the recording andreproducing system, the magnetic tape being connected to the pin bodywound around the shaft portion to form a roll having a predetermineddiameter.
 25. A magnetic tape cartridge comprising a cartridge casingformed of upper and lower casing halves, a single reel around which amagnetic tape is wound and which is contained in the cartridge casingfor rotation and a leader pin which is fixed to the leading end portionof the magnetic tape, the ends of the leader pin being removably held ina recess formed inside a tape outlet opening in the cartridge casing,wherein the improvement comprises that the recess has upper and lowerinner surfaces which are flat and spaced from each other by a distancesubstantially equal to the length of the leader pin, and upper and lowerguide surfaces are formed in the cartridge casing to extend from theupper and lower inner surfaces of the recess to the tape outlet openingso that the distance between the upper and lower guide surfaces becomeslarger toward the tape outlet opening.
 26. A magnetic tape cartridge asdefined in claim 25 in which a slide door for opening and closing thetape outlet opening is provided to be slid across the upper and lowerguide surfaces and the upper and lower end faces of the slide door areshaped to conform to the shape of the upper and lower guide surfaces.27. A magnetic tape cartridge as defined in claim 25 in which each ofthe guide surfaces is provided with a recess extending along the pathalong which the leader pin is drawn into the recess.
 28. A magnetic tapecartridge as defined in claim 25 in which the guide surfaces aresubjected to friction reduction treatment.